Fremont, California-based Cirrus Logic Inc has launched the CL-SH3350 Digital Read Channel, the second member of its single chip Partial Response, Maximum Likelihood read-write channel product family for hard disk drives. It is designed to be compatible with both the existing thin film and the emerging magneto-resistive head technologies but Cirrus reckons that its primary application is likely to be in magneto-resistive head drives. The chip supports user data rates of up to 84Mbps, making it the highest performance single-chip CMOS read-write channel on the market, claims Cirrus. The CL-SH3350 is designed to take advantage of the increased densities allowed by magneto-resistive heads using new-generation ‘d=0’ technology. The CL-SH3350 integrates all of the digital and analogue functions of a hard disk drive read-write channel into a single chip that requires only two decoupling and two bypass capacitors and a single external resistor, eliminating the 30 or more capacitive, resistive and inductive passive components that are required for equalisation and filtering in traditional analogue peak-detect read-write channels. It can also be used with thin film heads for drives that address the high-end market segment in which higher user data rates are required. The CL-SH3350 is based on the mixed-signal analogue system that Cirrus Logic developed for its first generation CL-SH3300 ‘d=1’ Partial Response, Maximum Likelihood read-write channel, which is intended for use in the thin film head environment. The CL-SH3350 is packaged in a 100-pin plastic quad flat pack. Samples of the new part are available now at a price of $27 each in quantities of 1,000, and volume production is promised for next quarter.
